Glaucoma causes progressive damage and death of retinal ganglion cells resulting in blindness. The prevalence of the disease is on the rise and it is estimated that 3 million Americans will be affected by 2020. Furthermore, an additional 3 to 6 million Americans have isolated elevated intraocular pressure (IOP) and are at risk of developing the disease. The overall goal of this study is to assess the prognostic significance of per papillary atrophy (PPA) progression during the course of ocular hypertension (OHT). The specific aims are: 1) To determine if PPA enlarges throughout the course of OHT, 2) To determine whether PPA progression in OHT individuals precedes and predicts the development of glaucoma, 3) To determine the rate of PPA progression before and after development of glaucoma, 4) To identify clinical and demographic baseline factors associated with PPA progression, and 5) To provide an indexed archive of the stereoscopic optic disc photographs of the Ocular Hypertension Treatment Study (OHTS) for future investigators. This project will use the data files of 3272 or 1636 subjects who participated in the OHTS, a National Institute of Health supported multicenter randomized clinical trial conducted in the United States to determine whether topical ocular hypotensive medications delay or prevent the development of glaucoma and subsequent vision loss in people with OHT. The OHTS data files contain demographic and clinical information including serial stereoscopic optic disc photographs collected from February 1994 through December 2008, which makes it the largest database of prospectively collected data obtained on OHT patients. Our hypothesis is that PPA progresses over time in OHT and that the progression precedes, and is predictive of the development of glaucoma. Slides of serial optic disc photos will be scanned and the images digitized to allow computerized measurements of PPA and optic disc areas. Progression of PPA area will be based on peripapillary atrophy-to-optic disc area ratio from baseline to the time of glaucoma conversion. The outcome of this study will have significance for identifying, within ocular hypertensive subjects, the subgroup of individuals at high risk of converting to glaucoma and determining the necessity of early treatment. This study will also enhance our understanding of the clinical significance of PPA progression in the development of glaucoma. PUBLIC HEALTH RELEVANCE: Although peripapillary atrophy (PPA) has been associated with glaucoma and ocular hypertension (OHT) in cross-sectional studies;it remains speculative whether PPA progression is a predictive factor for glaucoma in OHT patients. Identifying PPA progression as a predictive factor for glaucoma conversion in patients with OHT is of clinical and public health importance, as it will allow early treatment of ocular hypertensive subjects, based on the finding that lowering IOP prevents or delays the conversion to glaucoma. Early treatment may ultimately impact the incidence and prevalence of glaucoma.